Safety device for refrigeration system



25, 1964 F. PRITCHETT ETAL 3,122,001

SAFETY DEVICE FOR REFRIGERATION SYSTEM Filed Oct. 25, 1962 FIG. I

INVENTORS FREEMAN L. PRITCHETTG BY BILLY L MILLER fad/W 2 M UnitedStates Patent 3,122,001 SAFETY DEVICE FER REFREGERATION SYSTEM FreemanL. Pritchett, 3965 Steele St, and Billy L. Miller, 2933 Semrnes, both ofMemphis, Tenn., assignors of one-third to Ian F. Lockhart, Evansville,Ind. Filed Oct. 25, 1962, Ser. No. 233,004 Claims. (Cl. 62126) Thisinvention relates to a safety device in a refrigeration system. Moreparticularly, the present invention relates to a safety device that isresponsive to the presence of acid in the refrigerant of therefrigeration system.

The present invention is particularly useful with that type ofrefrigeration system which uses a so-called sealed compressor unit inwhich the coils of the compressor motor are exposed in a housing to therefrigerant and which housing also contains oil. In this type ofrefrigeration system, there has been the problem of burn-outs of themotor and deterioration of other parts due to the undesirable presenceof acid in the refrigeration system. This acid is caused by the presenceof water in the system, which combines with the refrigerant and the oilin the presence of heat to for-m hydrochloric and/ or hydrofluoricacids.

-'The present invention is directed towards overcoming the abovementioned and other problems in refrigeration systems.

Thus, one of the objects of the present invention is to provide a safetydevice which is responsive to acid in the refrigeration system so thatthe acid can be detected when in small amounts and before it can do anyharm.

A further object is to provide such a safety device which willautomatically shut off the compressor motor at the first indication ofacid in the system.

A further object is to provide such a safety device which actuates analarm to notify persons of the presence of acid in the refrigerationsystem.

A further object is to provide such a safety device that can easily bereset after it has been actuated so that the device is in condition tosubsequently detect the presence of acid in the system.

A further object is to provide such a device that is simple inconstruction and economical to manufacture.

A further object is to provide such a device which is positive in actionand highly efiective.

A further object is generally to improve the design and construction ofsafety devices in refrigeration systems.

The means by which the foregoing and other objects of the presentinvention are accomplished and the manner of ,their accomplishment willbe readily understood from the following specification upon reference tothe accornpanying drawings, in which:

FIG. 1 is a schematic diagram of a refrigeration system employing thesafety device of the present invention.

FIG. 2 is an enlarged plan view of the safety device of the presentinvention, with fragments of the inlet and outlet pipes being shown inconnection therewith.

FIG. 3 is a further enlarged fragmentary sectional view taken as on theline IIII'II of FIG. 2.

FIG. 4 is a side elevational view, with parts broken away for purposesof illustration, of a typical sealed compressor in use in the type ofrefrigeration system with which the device of the present invention isparticularly adapted to beused.

Referring now to the drawings in which the various parts are indicatedby numerals, and referring first more particularly to FIGS. 1 and 4, thetypical refrigeration system shown, with which the safety device 11 ofthe present invention is adapted to be used, comprises a unit 13 whichincludes an air-tight housing or casing 15 into the interior of whichflows the gaseous refrigerant R through an inlet pipe 17. A typical typeof refrigerant 3,122,001 Patented Feb. 25, 1964 used is so-calledRefrigerant 12, which has the formula of COlgFz and which is genericallyknown as dichlorodifluoromethane. It will be understood that other typesof refrigerants may be used in a system such as this, but the presentinvention is particularly useful with the refrigerants which for-m anacid when water is pres ent. It will be understood that the primaryreason for this type of sealed unit 13 is so that the refrigerant willcool the motor and so that the oil in small quantities will mix with therefrigerant and will lubricate the various parts of the system.

The coils 21 of the compressor motor 23 are mounted in the usual mannerin casing 15 and, as stated, are exposed to the refrigerant R. The usualvertical shaft 25 is driven by motor 23, and the shaft, in turn, drivesthe usual pump 27. The gaseous refrigerant -R is drawn in by pump 27through an inlet pipe 29, which is exposed to the interior of casing 15,and is exhausted through outlet pipe 31. It will be understood that thepart shown as at 33 in FIG. 4 is an oil pump also driven by shaft 25 andwhich pumps the oil to the various parts in the usual manner. -It isbelieved that the above general description of the typical sealed unit13 is deemed sufiicient since it is well-known to those skilled in theart and since it forms no part of the present invention.

From sealed unit 13 pipe 31 leads to the usual condenser 35, over whichthe usual fan 37 moves air so that the refrigerant R condenses back to aliquid and flows through pipe 39 to safety device 11, which will bedescribed more in detail later in the specification. :From safety device11, the refrigerant R flows through a pipe 41 to the usual dryer 43 fromwhere the refrigerant flows through a pipe 45 to the usual expansionvalve 47. Then, the refrigerant R flows from expansion valve 47 througha pipe 49 to the usual evaporator 51 which is disposed in the place tobe cooled, a for example, in a place to be air-conditioned orrefrigerated. From the evaporator 51, the refrigerant R flows throughinlet pipe 17 into the interior of casing 15, as heretofore described.From the foregoing description it can be seen that acid in the system,that is, in the refrigerant R, can do tremendous damage since thevarious parts and particularly the coils 211 are exposed to thisrefrigerant. Thus, the acid will eat through the insulation on coils 21,which will cause the coils to short-circuit and the motor to burn out.In addition, it can be seen that the other parts in the casing 15 andthroughout the system will be readily attacked by the acid.

Referring now more specifically to safety device 11, the safety devicecomprises an air-tight housing 53 which includes a base 55 and aremovable electrically insulated top 57. Base 55 includes a bottom 59and an integrally formed upstanding wall portion 61 around the peripheryof bottom 59. An annular internally threaded recess 63 is provided inthe upper end of wall portion 61, which recess establishes an annularshoulder 65 in wall portion 61. Top 57 is preferably disc-like in shapeand rests on shoulder 65, with an annular washer 67 preferably beinginterposed between top 57 and shoulder 65. An annular externallythreaded retaining ring 69, having slots 70 therein for engagement by asuitable tool for the turning thereof, is threadedly engaged in threadedrecess 63 and screwed down on top of top 57 to hold the top tightly inplace and seal the top to base 55. Thus, top 57 defines with theinterior of base 55 an enclosure '71 which is sealed off from theatmosphere.

Inlet pipe 39 extends through a bore 73 in wall portion 61 and is sealedtherein by suitable means, with the end of the pipe opening intoenclosure 71. In a similar manner, outlet pipe 41 opens into sealedenclosure 71 and leads therefrom through a bore 75 in wall portion 61where it is sealed therein by suitable means against leakage. From theforegoing it will be understood that the refrigerant R passes from pipe39, through sealed enclosure 71, and out pipe 41.

A rigid rocker arm 77 is pivotally mounted intermediate its ends inenclosure 71 for pivot about a horizontal axis as at 79. The means forpi'votally mounting rocker arm 77 is by any suitable means, andpreferably by a bracket 81 mounted on the lower surface of top 57 anddepending therefrom where the rocker arm is suitably pivotally attached.Rocker arm 77 is pivotable between a first position, shown in solidlines in FIG. 3, and a second position, shown in broken lines in FIG. 3.Resilient means, as a tension spring 33, is attached at oneend to top 57and attached adjacent the opposite end to the portion 85 of rocker arm77 which is to one side, or to the right, of pivot axis 79. For purposesof clarity, portion 85 will be herein designated the first end 85 ofrocker arm 77, and the portion or end to the left of pivot axis 79, asviewed in FIG. 3, will be designated second end 87. Spring 83, it willbe understood, urges rocker 77 to pivot counterclockwise, as viewed inFIG. 3. In other words, spring 33 urges rocker arm 77 to pivot in adirection from said first position towards said second position.

A holding member (59 engages rocker arm 77 to normally hold the rockerarm in said first position against the force of spring 83. Holdingmember 89 preferably comprises a bolt 91 and an element 93 attached tothe end of the bolt by suitable means, as an epoxy resin or otheradhesive or attaching methods. Bolt 91 is threadedly engaged in athreaded bore 95 through top 57 with the head 97 of the bolt 91 being onthe outside of top 57 and with the shank 1610f the bolt extendingclownwardly through the threaded bore 95 and below the lower surface. oftop 57 in such a position that the element 93 engages first end 85 ofrocker arm 77 to hold the rocker arm in said first position. A washer1&3 is preferably interposed between head 97 and top 57 in surroundingrelationship to shank H51 so that the device is sealed against leakage.It should be noted that the size of element 93 is less than the diameterof bore 5 so that holding member 85 can fit down into the bore. Element93 is preferably in the form of a solid cylinder so that the element is,in effect, an extension of shank ltll. Thus it will be understood thatwhen it is desired to replace holding member 89, this can easily be donemerely by unscrewing the used holding member and screwing in a new one.Also, it will be understood that, due to the threaded relationship ofbolt 91 and threaded bore 95, vertical adjustrnent of the element 93 ismade possible. Element 93 is formed of a material that is dissolvable byacids, such as hydrochloric and hydrofluoric acids, and the material ispreferably Zinc, although other acid dissolvable materials such asaluminum or the like may be used without departing from the spirit andscope of the present invention.

A pair of electrodes 105 and 107 respectively extend through bores 169and 111 in top 57 and are sealed therein against leakage, with theelectrodes extending above and below top 57 for a portion, as best seenin FIG. 3. Electrode 105 is positioned so that it serves as a contactfor rocker arm 77 and is in electrical contact with the rocker arm whenthe rocker arm is in said first position. The distal end of second end87 is preferably enlarged, as shown in FIG. 3, where the actualelectrical contact is made. Electrode 107 is electrically connected torocker arm 77 by means of a flexible conductor 113 that is attached atone end to electrode M7 by suitable means, as soldering or the like, andattached adjacent the other end to first end 35 of the rocker arm, as bysoldering or the like. The length of conductor 113 is such that therocker arm 77 is free to pivot between said first and second positionswithout any restraint by the flexible conductor. It will be understoodfrom the foregoing that a switch 115 is thus established by electrodes165, 107, flexible conductor 113, and rocker arm 77. Switch 115 ispreferably disposed in the electrical system of the refrigeration systemin such a manner that the switch is in series with the compressor motor23 and fan 37. Thus, the supply leads 117, 119 lead from the source ofelectricity, such as that indicated at 121, and switch is interposed inseries in lead 119, as by means of the leads 123, 125. Compressor motor23 is connected across supply leads 117, 119 beyond the switch 115, asby means of leads 127, 129, and fan 37 is connected in parallel withcompressor motor 23 across the supply leads, as by means of leads 131,133. From the foregoing it will be understood that as long as switch 115is closed, that is, when rocker arm 77 is in said first position,compressor motor 23 and fan 37 are energized, but that when the switchis opened, that is,- when the rocker arm moves away from the firstposition, the electrical circuit is broken and compressor motor 23 andfan 37 will stop running. Also, it will be understood that the abovedescribed opening of switch 115 will occur when acid gets into thesystem, which acid will dissolve the element 93, whereupon there will benothing holding rocker arm 77 in said first position, and it will pivotto said second position.

A third electrode extends through a bore 137 in top 57 and is sealedtherein against leakage, with the electrode extending above the top fora portion and depending therebelow where the lower end of the electrodeis preferably J-shaped so that it extends underneath rocker arm 77 andthence upwardly to its point of termination, in position to be contactedby the rocker arm when in said second position. Thus, a switch 1455 isestablished by electrodes 107, 135, flexible conductor 113, and rockerarm 77; which electrode 135, flexible conductor 113, and

rocker arm 77 are also common parts of the other switch I Suitableindicating means, such as a bell 151, is responsive to closing of switch149, and this circuit is preferably connected as follows: A lead 153extends from electrode 135 to bell 151, and another lead 155 alsoextends from the bell to a source of electricity, as a battery 157. Alead 159 extends from battery 157 to electrode 107. In other words,switch 149 is in series with battery 157 and bell 151 so that whenrocker arm 77 moves to said second position, the circuit is completedthrough the bell for the ringing thereof to warn persons that there isacid in the system. It should be noted that, if desired, the switch 115and its related wiring may be omitted, as for example, in cases where itis desired not to shut down the equipment but only to warn persons bythe indicating means 151 that corrective action should be taken.

From the foregoing description it will be understood that the safetydevice 11 of the present invention provides a very effective automaticmeans for preventing any damage to a refrigeration system, of the typeheretofore described, when any moisture gets into the system and isconverted to acids. Also, from the foregoing description it can be seenthat the holding member 89 can easily be replaced when a new one isneeded, and, if desired, a complete assembly of the rocker arm 77, top57, and the related parts can be easily replaced since the parts are allmounted as an assembled unit on top 57.

Although the invention has been described and illustrated with respectto a preferred embodiment thereof, it is to be understood that it is notto be so limited since changes and modifications may be made thereinwhich are within the full intended scope of this invention ashereinafter claimed.

We claim:

1. In a refrigeration system, a safety device comprising means providingan enclosure through which the refrigerant in said system flows, ahomogeneous and rigid element in said enclosure dissolvable in acids,means supporting said element in at least one fixed position in saidenclosure, and indicating means including a movable member contacted bysaid element and normally held in a first p sition by said element, saidindicating means he- 2) ing responsive to movement of said member fromsaid first position upon dissolution of said element to indicate thatacid is present in said system.

2. In a refrigeration system of the type having a compressor motorprovided with an eiectrical circuit for the operation thereof, a safetydevice comprising means providing an enclosure through which therefrigerant in said system flows, a homogeneous and rigid element insaid enclosure dissolvable in acids, and means supporting said elementin at least one fixed position in said enclosure, and means including amovable member contacted by said element and normally held in a firstposition by said element, said last mentioned means being connected intosaid electrical circuit and responsive to movement of said member fromsaid first position upon dissolution of said element to indicate thatacid is present in said system.

3. A safety device for use in a refrigeration system, said devicecomprising a housing providing a sealed enclosure therein; said housingincluding -a base, a removable top mounted on said base, and retainingmeans holding said top on said base; means attached to said housing andcommunicated with said enclosure for introducing the refrigerant intosaid enclosure, a rocker arm pivotally mounted in said enclosure forpivot between a first position and a second position, resilient meansattached to said rocker arm urging said rocker arm to pivot in adirection from said first position towards said second position, a firstelectrode sealingly extending through said top into said enclosure inposition to be contacted by said rocker arm when in said first position,a second electrode sealingly extending through said top into saidenclosure, flexible conductor means connecting said second electrode andsaid rocker arm, and holding means engaging said rocker arm for normallyholding said rocker arm in said first position against the force of saidresilient means, said holding means including means responsive to anacid to release said rocker arm from said first position.

4. A safety device for use in a refrigeration system, said devicecomprising a housing providing a sealed enclosure, said housing havingan internally threaded bore extending from the exterior of said housingto said enclosure, a bolt having a head on the exterior of said housingand a shank threadedly extending through said bore, an element attachedto said bolt to provide an extension thereof in said enclosure, saidelement being no larger than said shank whereby said element isremovable through said bore, a switch in said housing, means coupled tosaid switch for urging said switch towards the actuation thereof, saidelement engaging said switch for normally holding said switch againstthe actuation thereof, said element being responsive to an acid in saidenclosure to release said switch for the actuation thereof.

5. In a refrigeration system of the type having oil therein andincluding piping through which a refrigerant flows in contact with saidoil and a compressor motor provided with an electrical circuit for theoperation thereof, a safety device comprising means providing a sealedenclosure interposed in said piping in such a manner that therefrigerant flows through said enclosure, a rocker arm pivotally mountedin said enclosure for pivot between a first position and a secondposition, resilient means attached to said rocker arm urging said rockerarm to pivot in a direction from said first position towards said secondposition, holding means engaging said rocker arm for normally holdingsaid rocker arm in said first position against the force of saidresilient means, said holding means including an element exposed to therefrigerant in said enclosure, said element being formed of a materialthat is dissolvable by acids such as hydrochloric and hydrofluoric acidswhereby when acids such as hydrochloric and hydrofluoric acids arepresent in said system said element dissolves which releases said rockerarm and permits said rocker arm to pivot to said second position underthe influence of said resilient means, means in said electric circuit ofsaid motor responsive to movement of said rocker arm away from saidfirst position to shut off said motor.

6. In a refrigeration system of the type having oil therein andincluding piping through which a refrigerant flows in contact with saidoil and a compressor motor provided with an electrical circuit for theoperation thereof, a safety device comprising means providing a sealedenclosure interposed in said piping in such a manner that therefrigerant flows through said enclosure, a rocker arm pivotally mountedin said enclosure for pivot between a first position and a secondposition, resilient means attached to said rocker arm urging said rockerarm to pivot in a direction from said first position towards said secondposition, holding means engaging said rocker arm for normally holdingsaid rocker arm in said first position against the force of saidresilient means, said holding means including an element exposed to therefrigerant in said enclosure, said element being formed of a materialthat is dissolvable by acids such as hydrochloric and hydrofluoric acidswhereby when acids such as hydrochioric and hydrofluoric acids arepresent in said system said element dissolves which releases said rockerarm and permits said rocker arm to pivot to said second position underthe influence of said resilient means, means in said electric circuit ofsaid motor responsive to movement of said rocker arm away from saidfirst position to shut off said motor, and means responsive to movementof said rocker arm into said second position to indicate when saidrocker arm is in said second position.

7. The apparatus according to claim 6 in which said element is composedof zinc.

8. The apparatus according to claim 6 in which said element is composedof aluminum.

9. The apparatus according to claim 6 in which said element is composedof tin.

10. in a refrigeration system, a safety device comprising meansproviding an enclosure through which the refrigerant in said systemflows, a homogeneous and rigid element in said enclosure dissolvable inacids, a spring actuated switch, said element engaging said switch forholding said switch against the actuation thereof, said element beingresponsive to an acid in said enclosure to release said switch for theactuation thereof.

References Qited in the le of this patent UNITED STATES PATENTS MarshMar. 21, 1961

10. IN A REFRIGERATION SYSTEM, A SAFETY DEVICE COMPRISING MEANSPROVIDING AN ENCLOSURE THROUGH WHICH THE REFRIGERANT IN SAID SYSTEMFLOWS, A HOMOGENEOUS AND RIGID ELEMENT IN SAID ENCLOSURE DISSOLVABLE INACIDS, A SPRING ACTUATED SWITCH, SAID ELEMENT ENGAGING SAID SWITCH FORHOLDING SAID SWITCH AGAINST THE ACTUATION THEREOF, SAID ELEMENT BEINGRESPONSIVE TO AN ACID IN SAID ENCLOSURE TO RELEASE SAID SWITCH FOR THEACTUATION THEREOF.